// 纯函数和不纯函数
// slice / splice

let array = [1,2,3,4,5]

// 纯函数
console.log(array.slice(0,3))
console.log(array.slice(0,3))
console.log(array.slice(0,3))

// 不纯的函数
console.log(array.splice(0,3))
console.log(array.splice(0,3))
console.log(array.splice(0,3))

// 纯函数
function getSum(n1, n2) {
    return n1 + n2
}

console.log(getSum(1,2))
console.log(getSum(2,3))
console.log(getSum(3,4))